Method of making iron dextran-preparations

ABSTRACT

A substantially pure iron-dextran preparation is produced by a specific and simple process of reacting ferric chloride and dextran in aqueous solution in the presence of citric acid while maintaining the reaction temperature between about 50* C. and about 100* C. and the pH-value of the reaction mixture at a pH between about 9.0 and 10.0. The resulting iron-dextran preparation is substantially free of chloride ions. The novel process permits the preparation of iron-dextran preparations with a predetermined iron content.

United States Patent Christensen [451 Oct. 10, 1972 [54] METHOD OFMAKING IRON DEXTRAN-PREPARATIONS [72] Inventor: Henry MarinusChristensen,

Frederiksborgvej 107, Ny-Himmelev, 4000 Roskilde, Denmark [22] Filed:Nov. 3, 1969 [21] Appl. No.: 873,682

[52] US. Cl. ..260/209 D [51] Int. Cl. ..C08b 25/04 [58] Field of Search..260/209 D [56] References Cited UNITED STATES PATENTS 2,885,393 5/1959Herb ..260/209 D 3,151,107 9/1964 Heckel et a1 ..260/209 D 3 ,549,6 1 412/1970 Mioduszewski et al.260/209 D Primary Examiner-Lewis GottsAssistant Examiner-Johnnie R. Brown Attorney-Erich M. H. Radde [57]ABSTRACT A substantially pure iron-dextran preparation is produced by aspecific and simple process of reacting ferric chloride and dextran inaqueous solution in the presence of citric acid while maintaining thereaction temperature between about 50 C. and about 100 C. and thepH-value of the reaction mixture at a pH between about 9.0 and 10.0. Theresulting irondextran preparation is substantially free of chlorideions. The novel process permits the preparation of iron-dextranpreparations with a predetermined iron content.

METHOD OF MAKING IRON DEXTRAN- PREPARATIONS This invention relates to amethod of making Iron- Dextran preparations, i.e'. consisting partly ofiron and partly of a dextran compound selected from the group comprisingdextran, more and less depolymerized dextran and dextran derivatives.The preparations in question are suitable for parenteral use in medicalhuman and veterinary therapy and they can be used subcutaneously,intramuscularly and intravenously as well.

It is known that Iron-Dextran preparations can be used in the treatmentof iron deficiency anemia and can be injected either intramuscularly orsubcutaneously. Lately also specially produced preparations have beenused for intravenous injection.

The methods hitherto known for producing such preparations have beenquite complicated and even when exactly supervising the differentproduction steps and the materials used the resulting preparations havebeen of very varying character with regard to their content of both ironand dextran. Furthermore, in many cases the production has been timeconsuming and has been difficult to carry through, mainly due to thefact that during the process an undesirable gelatinizing of ferrichydroxide occurred, especially if the process was carried out underhighly alkaline conditions.

The methods used hitherto have often led to unsatisfactory results, asduring the coupling process of iron on dextran undesired sedimentatione.g. of ferric hydroxide took place.

The precipitation and purification processes carried out after couplingiron on dextran have been rather complicated and e.g. by processes wheredialysis has been used .-there has been a great possibility of undesiredformation of pyrogenic products as the production period was prolongedconsiderably.

Finally, by the methods used hitherto it has been difficult withcertainty to produce an iron dextran preparation in dry form which isvery pure as well as easily soluble and wherein the iron content is morethan percent calculated on dry material.

Moreover, it has not been possible even when exactly observing themethod stages to produce preparations with a predetermined iron contentwithin narrow limits 2 percent).

This is important in order to have a possibility of an uncomplicatedproduction of the final forms of medicaments containing iron dextran forhuman and veterinary use on the base of a well defined homogeneousstarting material.

By the present method it is possible to produce completely pure irondextran preparations also with a predetermined iron content of more than15 percent and in every case up to 40 percent without the appearance ofundesired precipitation or gelatinizing phenomena during the productionprocess.

Moreover, it is possible to carry out the process very fast so that therisk for appearance of pyrogens and bacterial growth is eliminated.

The characteristics of the production method is:

1. employment of a highly purified, ion-free dextran which e.g.corresponds to the purity demands of the 6 Pharmacopeias and has amolecular weight of 3 2. employment of a very pure ferric chloride,

3. that the process is carried out at a pH between 9 and 10,

4. that coupling of iron to dextran is carried out in the presence ofcitric acid, by which gelatinizing is avoided,

5. that coupling of iron to dextran is carried out under conditionswhereby a pyrogen-free solution of a pure dextran is mixed simultaneouswith a ferric chloride solution and a sodium hydroxide solution in suchproportions that the pH is kept constantly between 9 and 10, whilestirring 6. that the reaction is carried out at 50 C.

After coupling iron to dextran a clear solution of iron dextran isobtained from which iron dextran is precipitated by the addition ofisopropanol while stirring until such a concentration is obtained thatpractically all iron dextran is precipitated.

Thereafter stirring is discontinued and the supernatant liquid isdecanted carefully from the sediment.

The sediment is re-dissolved in ion free, pyrogen-free water, and whenthe dissolution is complete, the solution is filtered through Seitz El(-and particle filter to achieve a completely bacteria-free, clearsolution.

Thereafter the iron dextran is precipitated from the clear solution bymeans of ethanol while stirring.

When the precipitation is complete, stirring is discontinued. The liquidis decanted and the sediment is washed with concentrated alcohol tohalf-dryness and it is analyzed for its chloride content its amountshould be minimal.

The last purification step is repeated if necessary, if the chloridecontent is too high, and the finally precipitated sediment is thereafterdried under vacuum.

EXAMPLE 1 Production of Iron Dextran with 20 percent of Elementary lronBound on the Dextran Equipment:

1. a 1.000 liter reaction tank with steam-mantle and stirrer.

2. Containers for ferric chloride solution and sodium hydroxidesolution.

3. Fllter-Nutsche Sedimentation container with stirrer.

4. Filter-nutsche 5. Vacuum-dryer.

6. Plate Filter, Sparkler type.

Starting Materials 1. Water clear solution of pyrogene-free dextran withan average molecular weight of 7,000 in pyrogene-free distilled water,concentration 16 percent 72 kg. of dextran dissolved in water to a totalvolume of 450 liters.

2. Ferric chloride solution. 87 kg. FeCl,(6l-I,O) dissolved in about 150liters of pyrogene-free, distilled, hot water.

3. Sodium hydroxide solution, 34 B, about liters.

4. Citric Acid, 5 kg., B. P.

Method The dextran solution is heated in the reaction tank 5 understirring to 90 C. whereafter the citric acid is added and therein. Whenthe citric acid is dissolved, the sodium hydroxide solution being atroom temperature is added until the dextran solution is adjusted to a pHbetween 9 and 10.

When the pH is stable between these limits, the ferric chloride solutionand the sodium hydroxide solution are added simultaneously from the twocontainers, in which the solutions were prepared, into the reaction tankwhile stirring vigorously. Thereby the speed of flow of the twosolutions is regulated so that the pH of the reaction mixture is keptbetween 9 and 10.

Moreover, the speed of addition should not exceed about 80'liters perhour as far as the ferric chloride solution is concerned.

The temperature of the reaction mixture is controlled during the processand is kept between 80 C. and 90 C.

When the reaction is finished, the resulting solution is colled.down toroom temperature and the pH is adjusted by the addition of 5Nhydrochloric acid to 5.8.

The solution is now transferred to a sedimentation container withstirrer and isopropanol is added, until complete precipitation of irondextran is obtained.

The liquid is decanted from the sediment. Thereafter the precipitate isdissolved in the same volume of distilled, pyrogen-free water as beforeprecipitation whereby'a clear solution is obtained.

2 percent of activated carbon SECA S 3 and about 7 kg. of Hyflo SuperCel are added while stirring is continued.

The suspension is kept under constant stirring while it is graduallyfiltered through a plate filter with filter paper and immediatelythereafter through another plate filter with Seitz EK filter plates,whereby pyrogenfree, bacteria-free, practically sterile solution isobtained.

The filtered solution is collected in a sedimentation container andprecipitated with ethanol until complete precipitation takes place. Thesupernatant liquid is decanted, and the precipitate is washed a fewtimes with a small quantity of ethanol.

Thereafter the half-dry precipitate is transferred to a filter-nutscheand as much liquid as possible is filtered off by suction afterwhich thehalf-dry material is dried under vacuum.

The resulting iron dextran has a chloride content of 0.12 percent,.ispyrogen-free, and contains 20.1 percent of elementary iron.

EXAMPLE 2 Production of Iron Dextran Glycerol Glycoside containingpercent of Elementary Iron Bound on the Dextran For producing thiscompound, exactly the same method as described in example 1 is used withthe only alteration that the starting material is a Dextran GlycerolGlycoside of a molecular weight corresponding tothat stated for dextran.

With this starting material a final product is obtained which contains0.21 percent of chloride and 20.8 percent of elementary iron.

EXAMPLE 3 Production of Iron Dextran containing 36 percent of ElementaryIron Bound on Dextran In this example the procedure is exactly the sameas stated in example 1, but the starting materials used are as follows:

1. Water clear solution of pyrogen-free dextran of an average molecularweight of 7,000 in pyrogen-free distilled water,

concentration 15.8 percent 79 kg. of dextran dissolved in water to atotal volume of 500 liters 2. Ferric chloride solution, 225 kg.FeCl,(6H,O) dissolved in about 200 liters of pyrogen-free, distilled,hot

water.

3. Sodium hydroxide solution, 34 Be, about 270 liters.

4. Citric Acid, 5 kg. B.P.

The resulting lron Dextran showed a chloride content of 0.23 percent,was pyrogen-free and contained 35.9 percent of elementary iron.

EXAMPLE 4 Production of Iron Dextran with 15 percent of Elementary IronBound on the Dextran In this example the procedure is exactly the sameas in example 1, but the starting materials used are as follows:

1. Water clear solution of pyrogen-free dextran of an average molecularweight of 10,000 in pyrogenefree distilled water,

concentration 16 percent:

88 kg. of dextran dissolved in water to a total volume of 550 liters.

2. Ferric Chloride solutions, kg. FeCl 6H,O) dissolved in about litersof pyrogen-free, distilled, hot

water.

3. Sodium hydroxide solution, 34 Be, about 100 liters.

4. Citric Acid, 5 kg. B.P.

The produced iron dextran showed a chloride content of less than 0.1percent was pyrogen-free and contained 15.3 percent of elementary iron.

The examples described here demonstrate typical manufacturing results.

Employment of Dextran Glycoside as a starting material instead ofDextran has not shown any deviation in the results obtained.

The reason why isopropanol is used for the first precipitation andethanol for the second precipitation in the examples is that thisconstellation has appeared to be favorable to obtain agood salt freeprecipitation and regular final results, but it will be clear to everychemist that other precipitating agents as e.g. methanol or ketones orcombinations of such solvents can be used as well to obtaincorresponding results.

EXAMPLE 5 Production of Iron Dextran containing 25 percent of Elementarylron Bound on the Dextran.

In this example the procedure is exactly the same as in example 1, butthe starting materials used are as follows:

1. Water clear solution .of pyrogen-free dextran of an average molecularweight of 10,000 in pyrogene free distilled water, concentration 16percent:

72 kg. of dextran dissolved in water to a total volume of 450 liters.

2. Ferric Chloride solutions, 116 kg. FeCl,(6H,O) dissolved in about 70liters of pyrogen-free, distilled, hot water.

3. Sodium hydroxide solution, 34 Be, liters.

4. Citric Acid, 5 kg. B. P.

The produced iron dextran showed a chloride content of 0.05 percent, waspyrogen-free and contained 25.1 percent of elementary iron.

EXAMPLE 6 Production of Iron Dextran with 17 percent of Elementary lronBound on the Dextran In this example the procedure is exactly the sameas in example 1, but the starting materials used are as follows:

1. Water clear solution of pyrogen-free dextran of an average molecularweight of 10,000 in pyrogen-free distilled water,

concentration 16 percent:

72 kg. of dextran dissolved in water to a total volume of 450 liters.

2. Ferric Chloride solutions, 71 kg. FeCl (6l-l,O) dissolved in about 50liters of pyrogen-free, distilled water (hot).

3. Sodium hydroxide solution, 34 Be, about 95 liters.

4. Citric Acid, 5 kg. B. P.

The resulting iron dextran showed a chloride content of 0.08 percent,was pyrogen-free and contained 17 percent of elementary iron.

What I claim is:

1. In a process of producing an iron-dextran preparation by reacting adextran and an inorganic ferric salt dissolved in water, the improvementwhich consists in a. adding citric acid to an ion-free solution of ahighly purified, pyrogen-free dextran in pyrogen-free distilled water ofa temperature between about 50 C. and about 100 C., the amount of citricacid added being between about 72 parts and about 88 parts of dextranfor 5 parts of citric acid,

b. adding an alkali metal hydroxide solution to said mixture in anamount sufficient to adjust the pH- value of the mixture to a pH betweenabout 9.0 and about 10.0,

. simultaneously but separately adding a ferric chloride solution and analkali metal hydroxide solution to said mixture, while maintaining itstemperature between about 50 C. and about 100 C. and its pl-l-valuebetween a pH-value of about 9.0 and about 10.0, and

d. precipitating the resulting iron-dextran preparation from thereaction mixture.

2. The process of claim 1, in which the precipitated iron-dextranpreparation is further purified by dissolving it in pyrogen-freedistilled water and reprecipitating the purified iron-dextranpreparation.

3. The process of claim 1, in which precipitation of the iron-dextranpreparation in step (d) is effected by the addition of isopropanol.

4. The process of claim 2, in which reprecipitation of the iron-dextranpreparation is effected by the addition of ethanol.

5. The process of claim 1 in which ethanol is used as the dextranprecipitating solvent, the concentration of said solvent in step (a) isincreased to about 89 percent, the concentration of said solvent in step(d) is increased to about 95 percent, and the concentration of saidsolvent in step (e) is reduced by the addition of water to about 89percent.

6. The process of claim 1, in which the temperature during reaction iskept between about C. and about 7. The process of claim 1, in which thedextran reacted with ferric chloride has a molecular weight betweenabout 3,000 and about 20,000.

8. The process of claim 1, in which the dextran reacted with ferricchloride is dextran glycerol glycoside.

2. The process of claim 1, in which the precipitated iron-dextranpreparation is further purified by dissolving it in pyrogen-freedistilled water and reprecipitating the purified iron-dextranpreparation.
 3. The process of claim 1, in which precipitation of theiron-dextran preparation in step (d) is Effected by the addition ofisopropanol.
 4. The process of claim 2, in which reprecipitation of theiron-dextran preparation is effected by the addition of ethanol.
 5. Theprocess of claim 1 in which ethanol is used as the dextran precipitatingsolvent, the concentration of said solvent in step (a) is increased toabout 89 percent, the concentration of said solvent in step (d) isincreased to about 95 percent, and the concentration of said solvent instep (e) is reduced by the addition of water to about 89 percent.
 6. Theprocess of claim 1, in which the temperature during reaction is keptbetween about 80* C. and about 90* C.
 7. The process of claim 1, inwhich the dextran reacted with ferric chloride has a molecular weightbetween about 3,000 and about 20,000.
 8. The process of claim 1, inwhich the dextran reacted with ferric chloride is dextran glycerolglycoside.